Email Testing with miniRelay

miniRelay is a fantastic little Windows application that simulates an SMTP server on your local machine. This means you can do end to end testing of code that incorporates sending emails without the need to use your production email gateway.

Note that this is the best place to download miniRelay.

Once started, miniRelay will listen on port 25 (SMTP) at the IP (i.e. localhost). You can use the configuration button to change the listening port.


I did a quick test of miniRelay using the Email Message Catalog tester. This worked fine for sending emails within my own network but I couldn't get miniRelay to send emails to outside networks. This is most likely a network issue than a problem with miniRelay.

By the way, when an email is sent a sub-folder called queue is created in the miniRelay folder. To remove queued (waiting emails) that cannot be sent, simply delete the relevant .dat files from this folder.

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